JPH03289122A - X-ray mask structure - Google Patents

Abstract

PURPOSE:To prevent it from creating the projections of X-ray transmitting material or the surface from having flaws or dust by providing the side of a silicon wafer substrate with a cut. CONSTITUTION:A cut is provided at the side face of a silicon wafer. The cuts to be provided at the side face of this silicon wafer substrate shall be provided at one place or more of the same silicon wafer substrate, and for the shape, any shape will do so long as it is not grounded to the surface of the substrate holder or the silicon wafer when holding the silicon wafer with the substrate holder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an X-ray mask structure, and more particularly to an X-ray mask structure characterized by the shape of a silicon wafer serving as a supporting substrate.

(Prior Art) Conventionally, various methods have been used as lithography processing methods for electronic devices such as ICs and LSIs. Based on these properties, it has many advantages over conventional lithography methods using visible light or ultraviolet light, and is attracting attention as a powerful means of submicron lithography.

These X-ray mask structures use LP-CVD, plasma C
SiN, SiC, BN is deposited on the surface of a silicon wafer substrate by various CVD methods such as VD and ECR-CVD.
After forming an X-ray transparent film with a material such as, an etching protection film is provided on the back side of the silicon wafer substrate, and back etching is performed with a potassium hydroxide solution to expose the desired area of the X-ray transparent film. .

(The problem that the invention is trying to solve) However,
In the above conventional example, when forming an X-ray transparent film material on a silicon wafer substrate by various CVD methods, the X-ray transparent film material such as SiN is Abnormal growth may occur and protrusions of the X-ray transparent membrane material of several micrometers to ten-odd micrometers may occur. Also, when handling during film formation or lithography, XI! There were problems such as scratches and dust on the surface of the mask structure.

Therefore, an object of the present invention is to provide an excellent mask structure for X-ray lithography that solves the above problems.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides an X-ray mask structure comprising an X-ray absorber having a desired pattern, an Xll-transparent film that supports the absorber, and a support substrate that supports the X-ray transmission film, in which the support substrate is This is an X-ray mask structure characterized in that it is a silicon wafer with one or more notches provided on its side surface.

(Function) According to the present invention, by providing a notch on the side surface of the silicon wafer substrate, when an X-ray transparent film is formed on the surface of the silicon wafer, the substrate holder is not grounded on the surface, and various types of CVD can be performed. It becomes possible to deposit an X-ray transparent film material by a method or the like.

As a result, it is possible to prevent the formation of protrusions of the xB permeable film material on the surface of the silicon wafer substrate, and
Even during handling in other processes, scratches and dust can be prevented from forming on the surface, providing an X-ray mask structure with excellent characteristics.

(Preferred Embodiments) Next, the present invention will be described in more detail with reference to preferred embodiments shown in the accompanying drawings.

The X-ray transparent film used in the X-ray mask structure of the present invention is made of beryllium (Be), titanium (Ti), and silicon (Si).
In the present invention, any of the materials conventionally used as X-ray transmitting membranes, such as simple substances such as boron (B) or inorganic substances such as compounds thereof, or composite membranes of these inorganic films and organic films such as polyimide, can be used in the present invention. These X-ray transparent membranes have a 0.5
A thickness of ~5 μm is preferred.

Since the strength of these X-ray transparent films is insufficient, the X-ray transparent film is placed on a silicon wafer support substrate using LP-
Various CVD such as CVD, plasma CVD, ECR-CVD, etc.
The film is formed by method D.

Next, an etching protection film is provided on the back surface and etching is performed with an aqueous potassium hydroxide solution, thereby forming an inorganic membrane supported on the silicon wafer substrate.

As the Xll absorber formed on the above-mentioned X-ray transparent membrane, -
Substances with high U density 1, such as gold, platinum, tungsten, tantalum, copper, nickel, and thin films (for example, about 0.5 to 1 μm thick) of compounds containing them, used in conventional X11il mask structures Any of the X-ray absorbers listed above can be used in the present invention and is not particularly limited.

Such an X-ray absorber can be made by, for example, providing a plating electrode layer on the above-mentioned X-ray transmitting film, patterning a single-layer or multi-layer resist on the electrode layer by electron beam writing, and plating it with gold, for example. Form a gold pattern that is a line absorber. Alternatively, an Xll absorber can be formed by forming a film of tungsten, tantalum, etc. on an X-ray transparent film, forming a single layer or multilayer resist by electron beam writing, and then plasma etching the tungsten or tantalum layer. . Alternatively, the X-ray absorber may be formed before back etching the silicon wafer.

The present invention provides the structure of the X-ray mask structure as described above.
A feature is that a notch is provided on the side surface of the silicon wafer substrate. There are more than one notch on the side of the silicon wafer substrate, and the shape of the notch is such that when the silicon wafer is held in the substrate holder, the notch must be grounded to the surface of the substrate holder silicon wafer. Although the shape may be different, preferably the shape shown in FIGS. 1(a) to 1(c) is good.

In other words, as shown in Figure 1, the silicon wafer substrate has a notch, so when forming an X-ray transparent film, the silicon wafer substrate is only partially connected to the substrate holder of the film forming apparatus. will come into contact.

As a result, the X-ray transparent material was placed on the silicon wafer substrate with C
When deposited by VD method or the like, abnormal growth of the X-ray transparent material does not occur, and no protrusions of the X-ray transparent material occur.

Furthermore, during film formation and handling during the lithography stage, the silicon wafer substrate is in contact with the substrate holder only at this notch, so there is no chance of scratches or dust on the surface of the mask structure. .

Note that any method may be used to form the notch in the silicon wafer substrate, and examples thereof include dry etching, wet etching, polishing, and the like.

(Example) The details of the present invention will be explained below with reference to Examples.

Example 1 As shown in FIG. 1(a), two notches were made in the side surface of a silicon wafer substrate with a thickness of 2 mm and a diameter of 3 inches. On this silicon wafer substrate, S
An iC film was deposited to a thickness of 2 μm. A vertical furnace was used as the vapor deposition apparatus, and the wafer was held so that only two notches of the wafer were in contact with the holder.

In addition, the deposition conditions for the SiC film are as follows: 5i) IaC1 in the reaction gas.
□ and CJ2 were used, and H2 was used as a carrier gas.

Flow rate ratio (SiH*C1□/C2L) is 7, gas pressure is 8
torr and the substrate temperature was 1,000°C.

The SiC film thus formed had no protrusions or the like formed on its surface.

Next, a 1 μm thick tungsten nitride (WN) layer was formed as an X-ray absorber on this SiC by RF sputtering. A tungsten (W) target was used, and argon and nitrogen were used as gases. Gas flow ratio (Ar/Ni)
was 9, and the discharge power (RF power) was 0.2 KW. A 1 μm thick polyimide layer was formed on this WNX film, and a silicon-containing resist layer was further formed on the polyimide layer.

Next, the resist pattern is patterned by electron beam lithography, then the resist pattern is transferred to the polyimide layer by reactive ion etching (RIE) using oxygen gas, and then RI is performed using CF4+02 gas using this pattern as a mask.
The upper layer pattern was transferred to the WNx layer using E.

This substrate was back-etched from the back side with a KO)I aqueous solution to obtain an X-ray mask structure.

When handling in this series of steps was carried out by contacting only the notch formed on the side surface of the silicon wafer substrate, no scratches or dust were generated on the surface, and a good XI! A mask structure was obtained.

Example 2 As shown in Fig. 1(b), a silicon wafer substrate with a thickness of 2 mm and a diameter of 3 inches with four notches cut out on the side surface of the substrate was prepared as an X-ray absorber using the ECR-CVD method. A SiN film was deposited to a thickness of 2 μm.

The silicon wafer was held at two locations so that the holder did not come into contact with the silicon wafer surface. SiH4 and N2 were used as reaction gases, the flow rate ratio (SiH4/Ni) was 0.7, and the microwave power was 200W. The SiN film thus formed had no protrusions or scratches formed on its surface.

Subsequently, chromium and gold were successively deposited as a plating base layer on this SiN by EB deposition. Next, a PMMA resist was formed to a thickness of 1 μm, and the PMMA was patterned by EB drawing. After gold plating was performed on this by pulse plating, the PMMA was peeled off.

The prepared substrate was back-etched using a KOH aqueous solution to obtain an X-ray mask structure.

When handling in all of these steps was carried out using the notches in the substrate, a good X-ray mask structure was obtained with no scratches or dust attached to the surface of the substrate due to handling.

(Effects of the Invention) As explained above, by making a notch on the side surface of a silicon wafer substrate, it is possible to prevent the formation of protrusions in the X-ray transparent material during film formation and the damage caused by contact with the holder during handling. This has the effect of sufficiently suppressing the generation of dust and improving the performance and yield of the X-ray mask structure.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a substrate implementing the present invention. 1: Substrate

Claims (1)

[Claims] (1) In an X-ray mask structure consisting of an X-ray absorber with a desired pattern, an X-ray transparent film that supports the absorber, and a support substrate that supports the X-ray transparent film, the support substrate has a side surface. An X-ray mask structure characterized in that it is a silicon wafer with one or more notches formed in it.